Psych 2115 sept 30.docx

Psych 2115
Sept 30
Starting to talk about sense organs themselves
Starting with the Ear
Tuning fork: moving back and forth creating a sound wave that comes to your ear
Graph: pressure on y axis, distance on x axis
(just a wave going up and down)- typical sine wave
Pattern of high pressure, low pressure, high pressure, low pressure as the object
moves back and forth
This suggests you need a medium for the alternating patterns of pressure to travel
through
Trying to describe the waves:
1. Frequency: how often does it repeat itself, the frequency is measured in hertz (hz)
In any given medium, sound travels at the same rate as speed, there is a constant
rate of speed in a given medium, the rate of speed is constant so if something has a
higher frequency it has a smaller wavelength (repeating itself more often, smaller
distances between the peaks) - inverse relationship between wavelength and
frequency
2. Amplitude: how big is it? A reflection of the intensity of the vibration (bang the
tuning fork really hard, the sound wave has a high amplitude)- frequency wont
change, the wave lines will just go higher and deeper. Sound pressure level: unit is a
Bel. The bel unit is too big, it doesn’t effectively measure things- like using
kilometers to measure height. Instead people report things in tenths of bels, which
is a decibel. When using a description of the sound pressure level we use decibels.
Logarithmic scale- as you increase the amount of decibels by adding 10 (because it
is base 10 for logarithms) you are actually doubling the sound pressure level. So
something that is 10 decibels is only half as high in amplitude as something that is
20 decibels. 40 decibels is twice as intense as 30 decibels. Sound pressure level; how
much amplitude is put into it.
3. Phase of waves: a relationship between more than one wave- two waves relate to
each other in terms of phase
The sense organ for audition: the ear
The ear= the outer ear (the pinna). The pinna is designed to capture sound waves.
Captrues sound waves and send them through the auditory canal. The auditory
canal is small so when sound waves get in there the intensity gets ramped up. At the
end of the auditory canal we have the eardrum (tempanic membrane?). The eardrum can be punctures. On the other side of the eardrum you see a couple of
bones- malleus, (look up the other two bones): referred to as the stirrup, hammer,
and anvil (double check this)
These bones transmit the sound to the inner ear. They don't respond to low
frequencies so you don’t get overwhelmed by the low frequency sounds of your
body (heartbeat, etc.). They're rigid when they transmit information so theres very
little pressure loss when they do transmit these messages. One issue is that these
bones do pick up vibrations that come from inside of your head - listening to
yourself on a recording, when you say, "wow do I really sound like that?"- that’s
what your voice actually sounds like, you sound different to the world than to
yourself because you're not only hearing what's coming out of your mouth, you hear
the vibrations of these bones as well.
The cochlea is filled with fluid, when the oval window is pushed on it moves the
fluid in the cochlea, as you push in on the oval window that fluid needs somewhere
to go (it can't be compressed), its tension is relieved by the round window which
bulges out when this happens.
Take a cross section of the inner ear (looking into the cochlea, the curvy round sea
horse tail looking thing